| Summary: | 碩士 === 國立成功大學 === 光電科學與工程學系 === 106 === In this study, we used high-K materials, aluminum oxide, as a dielectric of organic thin-film transistors (OTFTs) to reduce the threshold and operating voltages. Polyimide (PI) was applied to n-type OTFTs as both insulator and electret in order to improve electrical characteristics and memory windows of OTFT-based memories. The electrical characteristics of the devices and the properties of PI films with various solid contents were measured by electrical and capacitative analyzers.
According to the electrical characteristics of OTFTs, the devices without PI showed large leakage current (gate current). The devices with PI performed enhanced channel current as well as low and stable gate current. Furthermore, we used different solid content of PI solutions to modulate the properties of PI layers. We observed that thinner PI film increased gate electric field to enhance carrier accumulation in n-type N,N’-ditridecylperylene-3,4,9,10-tetracarboxylic diimide semiconducting layer, improving the channel current of OTFTs. Based on the results of electrical measurements of devices, the OTFT-based memory devices with a PI layer spin-coated from 1.6 wt% solution have more trap states exiting in the interface between the PI and the active layers of devices, compared with those from other solid content of solutions.
The OTFT-based memory devices displayed a good retention of memory window under continuous operation. Moreover, the memory window of the device with PI layer from 1.6 wt% solution only decreased 16% after 2 hours’ operation. Surprisingly, a 500% increment of memory window of memory device was achieved by assisting a green laser beam during device operation. In summary, we have successfully fabricated a low-voltage operated organic memory device, in which the memory window has potential in industry production.
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